package rings

import "net/netip"

// RingZeroPrefix represents the backbone that connects gateways
// of the different Ring 1 networks.
//
// The ring 0 network corresponds to what would be ring 2 for region_id 0.
// 10.0.0.0-10.0.255.255
func RingZeroPrefix(region RegionID, zone ZoneID) (cidr netip.Prefix, err error) {
	switch {
	case !region.Valid():
		err = ErrOutOfRange(region, "region")
	case !zone.Valid():
		err = ErrOutOfRange(zone, "zone")
	default:
		addr := AddrFrom4(10, 0, uint(region)<<4+uint(zone), 0)
		cidr = netip.PrefixFrom(addr, RingZeroBits)
	}

	return cidr, err
}

// RingZeroAddress returns a Ring 0 address for a particular node.
//
// A ring 0 address looks like 10.0.(region_id << 4 + zone_id).(node_id)/20
func RingZeroAddress(region RegionID, zone ZoneID, node NodeID) (addr netip.Addr, err error) {
	switch {
	case !region.Valid():
		err = ErrOutOfRange(region, "region")
	case !zone.Valid():
		err = ErrOutOfRange(zone, "zone")
	case !node.ValidZero():
		err = ErrOutOfRange(node, "node")
	default:
		addr = AddrFrom4(10, 0, uint(region)<<4+uint(zone), uint(node))
	}

	return addr, err
}